tesla



(No Model.) 2 Sheets-Sheet 1.

N. TBSLA. APPARATUS FOR PRODUCING ELECTRIC GURRENTS OF HIGH FREQUENCY.

No. 577,670. Patented Feb. 28, 1897.

- (No Model.) 2 Sheets-Sheet 2,

NITESLA.

APPARATUS FOR PRODUCING ELECTRIC GURRENTS OF HIGH FREQUENCY.

No. 577,670. Patented Feb. 23, 1897.

nvvsu TOR WITNESSES f dwwnk TQM/6, By

, W M MM A TTOHNEYS NIKOLA TESLA, OF

APPARATUS FOR PRODUCING ELECTR PATENT @EEICE.

NEW YORK, IT. Y.

H) CURRENTS OF HIGH FREQUENCY.

SPECIFICATION forming part of Letters Patent No, 577,670, dated February23, 1897.

Application filed September 3, 1896.

To all whom, it may concern.-

Be it known that I, NIKOLA TESLA, a citi zen of the United States,residing at New York, in the county and State of New York, have inventedcertain new and useful improvements in Apparatus for Producing Flee tricCurrents of High Frequency, of which the following is a specification,reference being had to the drawings accompanying and forming a part ofthe same.

The apparatus for converting electric currents of ordinary characterinto those of high frequency, which I have heretofore shown anddescribed in applications for Letters Patent, has usually comprised acondenser and a circuit-controller operated by a suitable motive deviceand acting to alternately charge the condenser from a suitable source ofsupply and discharge it through a circuit of such character as to renderthe discharge one of very high frequency. For many purposes it has beenfound advantageous to construct the circuit-controller with insulatingand conducting segments of equal length, so that the condenser isconnected with its discharge-circuit during one-half of the time only.It follows from this that the working circuit, or that in which thehighfrequency currents are developed in form for practical application,receives such currents during only one-half the time.

For certain purposes it is desirable for economical operation that thereshould be no cessation of the flow of such currents, and my presentimprovements have been devised with the object of increasing the outputof a given apparatus by providing means by which, without materialadditions to or complication of such apparatus, high-frequency currentsmay be produced thereby continuously or without periods of rest.

Broadly stated, the improvement consists in the combination of twocondensers with a circuit-controller of such character and so operatedby a single motive device as to charge and discharge said condensersalternately, whereby one will be discharging while the other is beingcharged, and conversely.

In the drawings hereto annexed, Figure l is a diagrammatic illustrationof the arrangement and circuit connections of the invention. Fig. 2 is asectional view of a partof Serial No. L723. (N0 model.)

the commutator employed; and Fig. 0 is a diagram similar to that of Fig.1, illustrative of a modified embodiment of the invention.

Let A B designate the two conductors of any circuit from which theenergyis derived that is to be converted into a current of highfrequency.

0 is a circuit controller or commutator, a portion only for conveniencebeing shown in the figures. It is designed to be rotated by any suitablemotive device, of which, however, the shaft D only is shown, and itsplan of construction is as follows:

The letters 0 c designate two metal heads or castings with projectingportions d d, which, when the two heads are brought together and securedto a hub or shaft, intermesh, as shown in the drawings.

The spaces between two adjacent projections or bars (1 cl are equal inarc to the width of one of said bars and are filled in with blocks 0-,preferably of metal, insulated from the other conducting portions of thedevice. By the interposition of mica or other suitable insulatingmaterial the two heads or castings c c are insulate-d from each other.Upon the periphery of this commutator bear three brushes G G H, the twoformer resting upon the continuous metallic portions of the two heads,respectively, the latter being in position to bear upon the projections(Z d and blocks 6 alternately.

In order that the brushes may be capable of carrying any current whichthe operation of the apparatus may demand, they are made of largecrosssection, the brush H being approximately equal in width to one ofthe projections or segments d d, or to the space between adjacentsegments, so that in passing from one it comes into contact with thenext.

"he brush H is connected to the main 13 through a primary coil K of lowself-induction in inductive relation to a secondary L, which constitutesthe ultimate source of the current of high frequency which the apparatusis designed to develop and which feeds a circuit containing vacuum-tubesM, single terminal lamps M, or other suitable devices. The brushes G Gare connected with the main B through condensers N N, respectively, andto the main A through self-induction or choking coils O 0, these latterbeing used in order that the inductive discharge of the accumulatedenergy therein may be taken advantage of in charging the condensers.

The operation of the apparatus thus described is as follows: By therotation of the commutator O the brush H is caused to pass over theprojections (Z, closing the circuits through the primary K and the twocondensers alternately. These two circuits are so adjusted as to havethe same capacity, self-induction, and resistance. hen said brush is inelectrical connection with any projection d from the part c, the circuitis closed between mains A and B through coil 0, brush G, brush H, andcoil K. Energy is therefore accumulated in the coil 0. At the same timethe condenser N is short cireuited through the brush G, brush H, andcoil K, and discharges through this circuit the energy stored in it, thedischarge being in the form of a series of impulses which induce in thesecondary L corresponding impulses of high potential. lVhen brush Hbreaks the circuit through coil 0, the high-potential discharge or kickfrom the latter rushes into and recharges the condenser N, but as soonas the brush H has passed over the intervenin g block 6 and reached thenext segment (Z it closes the circuit through coil 0 and short circuitsthe condenser N, so that high-frequeney currents from either one or theother of the two condensers are flowing through the primary Kpractically without interruption. Thus without increasing the size orpower of the motive device or complicating in any material degree thecommutator these devices are made to perform double duty and the outputof the apparatus as a whole greatly increased. In Fig. 5 I haveillustrated a modified form of commutator for this apparatus, whichcomprises a disk E, of metal, but insulated from its shaft. Theperiphery of this disk is divided into conducting and insulated segmentsby the insert-ion therein of insulated metal blocks f. Thecircumferential width of these blocks is three times that of theconductingsegments f. A brush F bears upon a continuous metallic portionof the disk or upon a continuous ring in electrical connection with thesegments f and is connected with one terminal of the primary K. BrushesF F bear upon the periphery of the disk E and are connected to the mainB through the two conden sers, respectively. These brushes are capableof angular adjustment, so that they may be set to bear upon the disk atany two desired p oints.

From the explanation of the operation already given it is evident thatwhen the two brushes F F are set so that one leaves a segment f at theinstant that the other comes in contact with a segment 1'' the el'lectin charging and discharging the condensers is the same as in theprevious instance. The capability of varying the relations of thebrushes, however, which this form possesses has the advantage ofpermitting not only an alternate charging and discharge of thecondensers, but their simultaneous charging and discharge in multiplearc, whereby the frequency of the current of discharge is reduced.

It is also evident that all phase differences in the charging anddischarging of the con densers may in like manner be secured and thefrequency varied within wide limits. Of course the same motor andcircuit-controller might be made to charge more than two condensers insuccession and to discharge them in the same order.

\Vhat I claim is 1. The combination with a source of electric energy, ofa plurality of condensers and a discharge-circuit therefor, a motivedevice and a circuit-controller operated thereby and adapted to directthe energy of the source into the condensers and connect them with thedischarge-circuit successively and in alternation, as set forth.

2. The combination with a source of electric energy, of a motive device,two condensers, a circuit-controller adapted to direct the energy of thesource alternately into the said condensers, and a discharge-circuitthrough which, by the operation of said circuit-controller one condenserdischarges while the other is being charged, as set forth.

NIKOLA TESLA.

\Vitnesses:

M. Lawson Dyna, Danny W. COOPER.

